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A174785 Expansion of (1+2x-x^2+x^3-x^4-x^5)/(1+x^3)^2. 1
1, 2, -1, -1, -5, 1, 1, 8, -1, -1, -11, 1, 1, 14, -1, -1, -17, 1, 1, 20, -1, -1, -23, 1, 1, 26, -1, -1, -29, 1, 1, 32, -1, -1, -35, 1, 1, 38, -1, -1, -41, 1, 1, 44, -1, -1, -47, 1, 1, 50, -1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Hankel transform of A174783(n+1).

LINKS

Table of n, a(n) for n=0..50.

Index entries for linear recurrences with constant coefficients, signature (0,0,-2,0,0,-1).

FORMULA

a(n)=(n+4)*cos(pi*n/3)/3+n*sin(pi*n/3)/sqrt(3)-(n+1)*(-1)^n/3.

MATHEMATICA

CoefficientList[Series[(1+2x-x^2+x^3-x^4-x^5)/(1+x^3)^2, {x, 0, 50}], x] (* or *) LinearRecurrence[{0, 0, -2, 0, 0, -1}, {1, 2, -1, -1, -5, 1}, 60] (* Harvey P. Dale, May 11 2019 *)

CROSSREFS

Sequence in context: A210545 A141323 A210876 * A136789 A022661 A120292

Adjacent sequences:  A174782 A174783 A174784 * A174786 A174787 A174788

KEYWORD

easy,sign

AUTHOR

Paul Barry, Mar 29 2010

STATUS

approved

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Last modified December 5 23:36 EST 2019. Contains 329784 sequences. (Running on oeis4.)